File Format

Description

When a radio signal is represented digitally, it comprises a sequence of samples. A frequent sampling method used is I/Q sampling, where each sample is represented by an I component (in-phase component) and a Q component (quadrature component). One of the digital representations of an I/Q signal supported by the main signal processing tools is to have a sequence of samples, where each of the I and Q component in each sample are represented using floating numbers, between 0 and 1, on 32 bits, in little-endian mode. The diagram below displays this format:

+-------+-------+-------+-------+-------+-------+     +-------+-------+
|  i_0  |  q_0  |  i_1  |  q_1  |  i_2  |  q_2  | ... |  i_n  |  q_n  |
| (f32) | (f32) | (f32) | (f32) | (f32) | (f32) | ... | (f32) | (f32) |
+-------+-------+-------+-------+-------+-------+     +-------+-------+

The attached file file-format.iq contains a signal represented in the form described above. You need to separate the I and Q components and calculate the resulting SHA256 hash:

hash = SHA256(i_0 || i_1 || ... || i_n || q_0 || q_1 || ... || q_n)
flag = FCSC{<hash in lowercase>}

Notes:

• Note 1: || denotes concatenation, for instance: i_0 || q_0 = 20cebb3e || df342a3f = 20cebb3edf342a3f.
• Note 2: to solve this challenge, you only need to move bytes around, there is no need to decode float numbers in any way.